I've had back problems for years now, and I can't work my back and shoulders like I used to. It's just too painful. How does PH's (1-test/4ad stack) respond to muscles not being worked out?

I think they will make the pain worse.
I used them once and did gain some muscle but I think it's mostly water but I did push harder (placebo effect) and noticed an increase in joint pain.

If you use PH's and train the proper way and follow a specific diet and then once again use a proper PCT you will get some gains(minor in my opinion)...If your unable follow strict training and diet they will do more harm than good..

Stay away, most people who train and use PH's have not reached anywhere near thier full potential without using a hormone enhancer.I would focus on a good workout plan and solid diet and upping the intensity...